TY  - JOUR
A1  - Knoblauch, Christian
A1  - Beer, Christian
A1  - Liebner, Susanne
A1  - Grigoriev, Mikhail N.
A1  - Pfeiffer, Eva-Maria
T1  - Methane production as key to the greenhouse gas budget of thawing permafrost
JF  - Nature climate change
N2  - Permafrost thaw liberates frozen organic carbon, which is decomposed into carbon dioxide (CO2) and methane (CH4). The release of these greenhouse gases (GHGs) forms a positive feedback to atmospheric CO2 and CH4 concentrations and accelerates climate change(1,2). Current studies report a minor importance of CH4 production in water-saturated (anoxic) permafrost soils(3-6) and a stronger permafrost carbon-climate feedback from drained (oxic) soils(1,7). Here we show through seven-year laboratory incubations that equal amounts of CO2 and CH4 are formed in thawing permafrost under anoxic conditions after stable CH4-producing microbial communities have established. Less permafrost carbon was mineralized under anoxic conditions but more CO2-carbon equivalents (CO2Ce) were formed than under oxic conditions when the higher global warming potential (GWP) of CH4 is taken into account(8). A model of organic carbon decomposition, calibrated with the observed decomposition data, predicts a higher loss of permafrost carbon under oxic conditions (113 +/- 58 g CO2-C kgC(-1) (kgC, kilograms of carbon)) by 2100, but a twice as high production of CO2-Ce (241 +/- 138 g CO2-Ce kgC(-1)) under anoxic conditions. These findings challenge the view of a stronger permafrost carbon-climate feedback from drained soils1,7 and emphasize the importance of CH4 production in thawing permafrost on climate-relevant timescales.
Y1  - 2018
U6  - https://doi.org/10.1038/s41558-018-0095-z
SN  - 1758-678X
SN  - 1758-6798
VL  - 8
IS  - 4
SP  - 309
EP  - 312
PB  - Nature Publ. Group
CY  - London
ER  - 
TY  - JOUR
A1  - Coch, Caroline
A1  - Lamoureux, Scott F.
A1  - Knoblauch, Christian
A1  - Eischeid, Isabell
A1  - Fritz, Michael
A1  - Obu, Jaroslav
A1  - Lantuit, Hugues
T1  - Summer rainfall dissolved organic carbon, solute, and sediment fluxes in a small Arctic coastal catchment on Herschel Island (Yukon Territory, Canada)
JF  - Artic science
N2  - Coastal ecosystems in the Arctic are affected by climate change. As summer rainfall frequency and intensity are projected to increase in the future, more organic matter, nutrients and sediment could bemobilized and transported into the coastal nearshore zones. However, knowledge of current processes and future changes is limited. We investigated streamflow dynamics and the impacts of summer rainfall on lateral fluxes in a small coastal catchment on Herschel Island in the western Canadian Arctic. For the summer monitoring periods of 2014-2016, mean dissolved organic matter flux over 17 days amounted to 82.7 +/- 30.7 kg km(-2) and mean total dissolved solids flux to 5252 +/- 1224 kg km(-2). Flux of suspended sediment was 7245 kg km(-2) in 2015, and 369 kg km(-2) in 2016. We found that 2.0% of suspended sediment was composed of particulate organic carbon. Data and hysteresis analysis suggest a limited supply of sediments; their interannual variability is most likely caused by short-lived localized disturbances. In contrast, our results imply that dissolved organic carbon is widely available throughout the catchment and exhibits positive linear relationship with runoff. We hypothesize that increased projected rainfall in the future will result in a similar increase of dissolved organic carbon fluxes.
KW  - permafrost
KW  - hydrology
KW  - lateral fluxes
KW  - hysteresis
KW  - climate change
Y1  - 2018
U6  - https://doi.org/10.1139/as-2018-0010
SN  - 2368-7460
VL  - 4
IS  - 4
SP  - 750
EP  - 780
PB  - Canadian science publishing
CY  - Ottawa
ER  -